The present invention is generally related to devices, systems, and methods for separating crops from extraneous plant materials, and in particular, provides a crop separator to separate canes and leaves from dried on the vine raisins, twigs and sticks from tree crops such as olives, and other problematic harvesting byproducts from the desired crop.
Raisins sold in the United States have traditionally been dried in the sun after picking. The picked raisins are often placed on drying trays or strips of paper. These trays or paper strips are then placed on dirt mounded or terraced between the rows of vines. It usually takes about three weeks to sun dry raisins in the Central Valley of California, the leading raisin production region in the United States.
Although the traditional dried-on-the-ground methods for producing raisins are both simple and cost effective, this technique does have significant disadvantages. One particular disadvantage of dried-on-the-ground raisin production is the possibility of rain during the drying season. Rain which occurs during the three week drying period increases the susceptibility of the raisins to mold, infestation, and rot, and can potentially ruin the crop. Also, especially under more humid conditions, raisins may be attacked while on the ground by certain molds or mildew which can ruin them for human consumption. Another significant problem with dried-on-the-ground raisins is the cost associated with the separate production process steps: picking the grapes, placing the trays on the dirt mounds formed between the rows, and gathering the raisins after they have dried.
A variety of alternative methods for producing raisins have been proposed with varying degrees of success. Efforts have been made to mechanically harvest green grapes and automatically deposit them onto strips of drying paper between the rows. Unfortunately, because of the violence with which grapes are mechanically harvested, a certain amount of damage occurs to the grapes, leaving the grapes sticky. While this is not a problem if the grapes are immediately crushed (such as when making wine) leaving damaged grapes on trays on the ground may create lower raisin quality and could promote the growth of molds and mildew, as well as insect damage.
Still further grape production methods have been used. Raisins having a golden color may be produced by dipping the grapes in a caustic soda and water solution, exposing the dipped grapes to sulfur and carbon dioxide, and then drying the exposed grapes in a dehydrator. Alternatively, green grapes may be dipped in a hot water solution to split the skins and to promote drying. In Australia, green grapes are sprayed with an oil emulsion (typically 2% aqueous solution of methaloleate and potassium carbonate) to create tiny cracks in the skin which aid drying, as well as to produce a lighter color raisin.
An alternative Australian raisin production raisin system, sometimes called the Irymple Trellis System, dries the raisins on the vine prior to harvesting. In that system, the fruiting canes are supported on a horizontal trellis system along one side of the row, while replacement canes are supported along a reclined trellis system on the other side of the row. The fruit develops from the fruiting canes and hangs freely below a leaf canopy. When the fruit is mature, the grape bunches are sprayed with an oil emulsion, such as methaloleate, and the fruiting canes are cut to speed drying of the grapes. It has been found that limiting the number of cut canes to no more than about 50% of the total canopy avoids injuring the vine and reducing the next year's harvest. U.S. Pat. No. 5,557,883, the full disclosure of which is incorporated herein by reference, describes an improved trellis system and method which are particularly well suited for supporting grape vines to produce dried-on-the-vine raisins.
While dried-on-the-vine raisin production methods offer significant advantages over dried-on-the-ground methods, harvesting of the dried raisins remains somewhat problematic. In particular, canes and other plant materials are often detached from the vines when grapes and other vine crops are mechanically harvested. These tough, elongate canes can play havoc on the harvesting and collecting equipment. The relatively light weight of a dried-on-the-vine raisin and the presence of the severed canes makes the separation of the dried raisins from the cane both particularly important and particularly difficult.
In light of the above, it would be advantageous to provide improved devices, systems, and methods for separating canes and other plant material from crops, particularly from dried-on-the-vine raisins. It would be particularly advantageous if these improved techniques were adapted for use in the fields with the harvesting equipment, so as to avoid the damage and delays which result from handling the combined crop and plant materials.